WO1996009930A1

WO1996009930A1 - Heat-shrinkable polyolefin laminate film

Info

Publication number: WO1996009930A1
Application number: PCT/JP1995/001914
Authority: WO
Inventors: Shuichi Morita; Koji Sueoka; Fumio Horita; Toshikatsu Oyama; Hideo Isozaki
Original assignee: Kohjin Co., Ltd.
Priority date: 1994-09-29
Filing date: 1995-09-22
Publication date: 1996-04-04
Also published as: DE69502171T2; EP0732196A1; JPH0899393A; KR100317008B1; EP0732196A4; DE69502171D1; JP3258830B2; DK0732196T3; KR960706399A; US5691049A; EP0732196B1

Abstract

A heat-shrinkable polyolefin laminate film composed of a crystalline polypropylene resin as the surface layers and an ethylenic resin composition essentially comprising linear low-density polyethylene and syndiotactic polypropylene as the intermediate layer and having been stretched at least twofold in both the longitudinal and transverse directions. The film does not undergo a lowering in transparency even when the intermediate layer contains reclaimed material, is excellent in low-temperature shrinkability and the adaptability to wrapping machines, and is suitable as a heat-shrink wrapping material.

Description

Technical damage Polyolefin-based heat-shrinkable laminated film

The present invention relates to a polyolefin-based heat-shrinkable film, and more particularly, to a linear low-density polyethylene and a syndiotactic as an intermediate layer. The present invention relates to a heat-shrinkable laminated film that is excellent in transparency and low-temperature shrinkage using an ethylene resin composition essentially consisting of chip polyprovirene. . Background art

Heretofore, polyvinyl chloride film, polyethylene film, polypropylene film, etc. have been known as heat-shrinkable packaging materials. Power, low cost, ease of disposal after use, etc., polyrefin-based heat-shrinkable polyolefins such as polyethylene and polyprovirene. Rooms are preferred. However, among these, the polystyrene-based heat-shrinkable film has a low rigidity, which is characterized by its excellent impact resistance. However, it has disadvantages such as difficulty in high-speed packaging. Polypropylene-based heat-shrinkable films, on the other hand, are rigid and have excellent suitability for packaging machines, but have the drawback of not shrinking at relatively high temperatures. ing.

As a method for solving the above-mentioned drawbacks, the inventors of the present invention have proposed an integrated heat shrinkage method comprising a polystyrene resin layer and a polypropylene resin layer. A film has been proposed (Japanese Patent Laid-Open No. 63-173641).

The film is an excellent heat-shrinkable film that has both low-temperature shrinkage and stiffness.However, film pieces generated during the manufacturing process and films that do not conform to product standards are produced. (Hereinafter referred to as “collected items”), there was a problem that transparency was reduced at the pedestal where it was recycled. Disclosure of the invention The inventors of the present invention have made various studies for a heat-shrinkable film that has solved the above-mentioned disadvantages, and as a result, have reached the present invention.

That is, according to the present invention, the density at 25 ° C. is 0.91 to 0.93 gzcm, and the methyl index force i ′ O. Linear low-density polyethylene (ン) consisting of 80% to 50% by weight of synotactic polipolyvinyl (ン) and α-olefin Β) The intermediate layer is made of a styrene resin composition essentially consisting of 20 to 50 parts by weight, and the surface layer is made of a crystalline polypropylene resin. Thickness is 30% or more of the total, surface layer thickness is 1m or more each, and stretched 2.0 times or more in each of vertical and horizontal directions.Excellent low-temperature shrinkage and recycled products are recycled. It is intended to provide a polyolefin-based heat-shrinkable laminated film which does not cause a decrease in transparency in the case of heat-shrinkage.

Hereinafter, the present invention will be described in detail.

In the present invention, a straight-shaped low-density polyethylene (Α) composed of ethylene and α-olefin used as one component of the intermediate layer is 25 . The density in C ranges from 0.91 to 0.93 g / cm and the melt indexing power is from 0.2 to 3.008 min. Those having a density of less than 0.9 lg Z cm ⁵ are not preferred because the effect of improving the waist is small and the transparency when the collected product is recycled is reduced. , 0.93 8. Exceeding π ^ is not preferred because the low-temperature shrinkage is insufficient. A melt index of less than 0.2 g / 10 minutes is not preferred because it increases the load on the melt extrusion. It is not preferred that / 'exceeds 10 minutes, because the stability in the stretching step becomes poor. In addition, α-amino acids copolymerized with ethylene include butene-11, pentene-11, hexene-11, and heptene-11. One or two selected from the group consisting of octene-11, 4-methylpentene-11, decene-11, pendecene-11 and dodecene-11 Preferably it is at least species. The mixed amount of the linear low-density polyethylene is from 80 to 50 parts by weight, and if the amount is less than 50 parts by weight, the low-temperature shrinkage property and the impact resistance are deteriorated. Not good.

The syringe used together with the linear low-density polyethylene for the intermediate layer of the present invention. The tactic polypropylene (B) has the lowest syndiotacticity obtained by using conventional catalysts. Unlike the tactic polypropylene, the cysteine has a syndiotactic pentad fraction of 0.7 or more measured by ¹³ C-NMR. It is the best polypropylene in geotacticity. Such a syndiotactic polypropylene is disclosed in, for example, Japanese Patent Application Laid-Open Nos. HEI 2 (1996) -41303, JP-A-2-41130, and Japanese Unexamined Patent Application Publication No. Hei 2-2 74703, Japanese Unexamined Patent Application Publication No. Hei 2 — 274 074, Japanese Unexamined Patent Application Publication No. Heisei 3-179905, Japanese Unexamined Patent Application Publication No. Hei 3-179006 And the like, and can be obtained by using a catalyst comprising a crosslinked transition metal compound having asymmetrical ligands and a cocatalyst as described in US Pat. A method for measuring the syndiotactic pentad fraction by ¹³ C-NMR is described in, for example, JP-A-2-41303. It can be determined by such a known method. The mixed amount of this syntactic polypropylene is 20 to 50 parts by weight, and if less than 20 parts by weight, the recovered product is recycled. It is not preferable because the effect of improving the transparency of the table is small. It should be noted that, in addition to the above resin composition, the intermediate layer is mixed with the crystalline polyprovirene of the surface layer on the base where the recovered product is recycled. Yes, to the extent that it does not support the purpose of the present invention, other resins, for example, high-pressure polystyrene, polyethylene-butyl acetate copolymer base, Ionomer, propylene-butene copolymer, etc. can be mixed and used.

The crystalline polypropylene used for the surface layer of the present invention is a publicly known one, and is a propylene-ethylene copolymer mainly composed of propylene and a propylene copolymer. Ethylene'butene terpolymer or a mixture of these polymers and a thermoplastic polymer capable of forming a mixed film is used. The propylene.ethylene copolymer and the propylene ヱ “ethylene” butene terpolymer are ethylene or ethylene copolymers. It contains 2 to 10 wt% of ethylene butene, and as a thermoplastic polymer that can be formed into a film by mixing with these polymers, ethylene / vinyl acid copolymer is used. The present invention includes polymers, polyethylene / α-olefin copolymers, propylene / butene copolymers, ionomers, polybutenes, and petroleum resins. Purpose It can be used as long as no branch is provided.

In the present invention, the intermediate layer does not necessarily have to be a single layer, and may be 2 or more layers if necessary. The thickness of the intermediate layer must be 30% or more of the whole, and if it is less than 30%, sufficient low-temperature shrinkability cannot be obtained. Further, the thickness of the surface layer made of the crystalline polypropylene resin is at least 1ί ί, and preferably at least 2 m. . If the thickness of the surface layer is less than 1 m, the good suitability of the crystalline polypropylene resin for the packaging machine cannot be sufficiently exhibited, and the heat resistance during shrinkage is poor. In addition, if desired, additives such as lubricants, anti-picking agents, antistatic agents, and anti-delta agents are appropriately used for the purpose of providing their effective effects. This is effective, especially when added to the surface layer.

Next, a method for producing the film of the present invention will be described. The method for producing the stretched film of the present invention using the resin described above can be performed by a known method.Hereinafter, a case of three-layer annular film forming and stretching will be described as an example. This will be explained specifically.

First, the mixed bed composition composed of the above-mentioned straight-shaped low-density polyethylene, syndiotactic poliv π-viren and the recovered product was used for the intermediate layer and the crystallinity. The polypropylene resin is melt-kneaded by three extruders so that it becomes a surface layer, co-extruded by a three-layer annular die, and once stretched without being stretched. It is quenched and solidified to produce a tube-shaped unstretched film.

The obtained tube-stretched unstretched film is supplied to, for example, a tube-stretching apparatus as shown in FIG. A simultaneous biaxial orientation is caused by expansion and stretching by applying a gas pressure inside the tube at a temperature lower than 10 ° C, preferably below 15 ° C, preferably below 10 ° C. The stretching ratio is not necessarily required to be the same in the vertical and horizontal directions. More preferably, it is stretched three times or more. The finale taken out of the stretching device can be annealed as desired, and this annealing prevents natural shrinkage during storage. It can be. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic cross-sectional view of a tuber biaxial stretching apparatus used in Examples.

(1. Unstretched film, 2. Low speed nibble, 3. High speed nibroll, 4. Preheater, 5. Main heater, 6. Cooling ring, 7. Folded rolls) Best mode for carrying out the invention

Hereinafter, the present invention will be described in more detail with reference to examples; however, the present invention is not limited to these examples. In addition, each physical property shown in this Example was determined by the following method.

① Overall thickness

No, measured with a micro-meter.

② Thickness of surface layer

The thickness of the surface layer was measured by observing the cross section of the film with a microscope.

③ Haze

It was measured by JIS-K6714.

④ Gross (60 °)

JIS — Set by Z8741.

⑤Area shrinkage

Films cut into squares of 10.0 cm each in vertical and horizontal directions were immersed in a 100 ° C glycerin bath for 10 seconds, quenched in water, and then vertically and horizontally. The length of each was measured and calculated by Equation 1.

Area shrinkage (%) = 100-A X B (Equation 1)

(However, A and B indicate the vertical and horizontal lengths (cm) after quenching, respectively.)

⑥ Suitability for packaging machine

Using an automatic wrapping machine (model PW-R2, pillow wrapping machine) manufactured by Tokiko Kogyo Co., Ltd., wrap the power bracket with 100-minute beads and check the packing condition. O observed Example 1

As shown in Table 1, the surface layer was made of a propylene-ethylen random co-base having an ethylene content of about 4.2% by weight, and the density was 0.9. 1 6 g / cm ^5, MI force 'l. 2 g, 1 linear low density Po Li We Chi Le emissions 8 0 by weight portion and Thin-di O data Figure 6-2 Operation manually I with 0 minutes characteristics One way; 0.79, Ml is 4.9 g / 10 minutes (manufactured by Mitsui Toatsu Chemicals, Inc.). Syndiotactic Polypropylene 20 By weight, the mixture composition was mixed and kneaded at 170 ° C to 240 ° C with three extruders to obtain the thickness ratios shown in Table 1. The extrusion rate of each extruder was set as described above, and co-extrusion was performed downward from a three-layer annular die held at 240 mm.

The formed three-layer tube is used to swing the outer surface of the cylindrical cooling mandrel through which the cooling water circulates, while passing the outside through a water tank. The film was further cooled and taken off to obtain an unstretched film having a diameter of 75 mm and a thickness of 240; um. This tube-shaped unstretched film is guided to the tuber biaxial stretching apparatus shown in Fig. 1 and stretched 90 times to 110 times four times in each of the length and width directions. A biaxially stretched film was obtained. Next, the stretched film was treated with 75 pieces of hot air for 10 seconds in a tube annealing device, cooled to room temperature, folded, and wound up.

The stability during stretching was good, there was no vertical movement of the stretching point or swing of the stretching tube, and no uneven stretching state such as necking was observed. The obtained stretched film had a thickness ratio as shown in Table 1, and was excellent in transparency, gloss, and low-temperature shrinkability. In addition, in the evaluation of packaging using a billow packaging machine, it was found that the heat seal temperature and the shrinkage tunnel temperature showed good suitability for the packaging machine over a wide temperature range. It was a

Example 2

Except that the film produced in Example 1 was made into a repellent by a twin-screw extruder and 30 parts by weight of the repelled (recovered product) was mixed with the intermediate layer, In the same manner as in Example 1, a product S biaxially stretched film having a thickness ratio shown in Table 1 was obtained. Next, this stretched film is applied to a tube annealing device 75. C hot air After treating for 10 seconds, the mixture was cooled to room temperature, folded and wound up.

The stability during stretching was good, there was no vertical movement of the stretching point or swing of the stretching tube, and no uneven stretching state such as necking was observed. The obtained stretched film had a thickness ratio as shown in Table 1, and was excellent in transparency, gloss, and low-temperature shrinkability. In addition, in the packaging evaluation using a Pillow packaging machine, even if the heat seal temperature and the shrinkage tunnel temperature have good packaging machine suitability over a wide temperature range. It was a

Example 3

The same propylene-ethylene random copolymer as in Example 1 was used for the surface layer, and the same linear low-density polyethylene and syndio as in Example 1 were used. A composition obtained by mixing 50% by weight of each of the tactic polypropylenes was used as an intermediate layer, and a stretched film having a thickness ratio shown in Table 1 was prepared in the same manner as in Example 1. The system was made. This stretched finolem has a haze of 2.4% glosser; 135% and area shrinkage of 41%, and has good suitability for packaging machines. Was. Next, the stretched film was repelled by a twin-screw extruder.

30 parts by weight of this revelet, 50 parts by weight of the above-mentioned straight-shaped low-density polyethylene and 50 parts by weight of syndiotactic polypropylene The composition obtained by mixing the above components was used as an intermediate layer, and the above-mentioned propylene ethylene random copolymer was used as a surface layer. A stretched film having a thickness ratio was obtained. Next, the stretched film was treated with hot air at 75 ° C for 10 seconds in a tube annealing apparatus, cooled to room temperature, folded, and wound up. The stability during stretching was good, there was no vertical movement of the stretching point or swing of the stretching tube, and no uneven stretching state such as necking was observed. The obtained stretched film had a thickness ratio as shown in Table 1, and was excellent in transparency, gloss, and low-temperature shrinkage. In addition, in the packaging evaluation using a single-end packaging machine, a product that has good suitability for packaging machinery over a wide temperature range, including both heat seal temperature and shrinkage tunnel temperature. Met.

Example 4

Probilen / ethylene random with weight of 3.4% by weight 70% by weight of a linear low-density polyethylene having a base body as a surface layer, a density of 0.925 g / cm ³ and an MI of 1.6 g / l 0 Y The composition obtained by mixing 30 parts by weight of cupoliprovirene was used as an intermediate layer, and the composition was as shown in Table 1 in the same manner as in Example 1. A stretched film having the thickness ratio shown was produced. This stretched film has a haze force s of 2.6%. Grossa: 13.4%, an area shrinkage of 41%, and has good suitability for packaging machines. There was. Next, the stretched film was repelled by a twin-screw extruder.

40 parts by weight of this revelet, 70 parts by weight of the above-mentioned straight-shaped low-density polystyrene and 30 parts by weight of syndiotactic polypropylene In the same manner as in Example 1, as shown in Table 1, the composition obtained by mixing the above components was used as an intermediate layer, and the above-mentioned propylene / diethylene random co-supporting body was used as a surface layer. A stretched film having a thickness ratio was obtained. Next, the stretched film was treated with 75 pieces of hot air for 10 seconds in a tube annealing apparatus, cooled to room temperature, folded and wound ₍ during stretching). The stability of the film was good, there was no vertical movement of the drawing point and no fluctuation of the drawing tube, and no uneven drawing state such as necking was observed. The stretched film had a thickness ratio as shown in Table 1 and was excellent in transparency, gloss, and low-temperature shrinkage. However, both the heat seal temperature and the shrink tunnel temperature had good suitability for packaging machinery over a wide temperature range.

Comparative Example 1

The same low-density polystyrene as in Example 1 was used at 80% by weight, using the same provylene / chilen random copolymer as the surface layer, and the same low-density polyethylene as in Example 1 as the surface layer. The same layer as that of the surface layer, a composition obtained by mixing 20% by weight of ethylene rubber copolymer was used as an intermediate layer, and the composition is shown in Table 1 in the same manner as in Example 1. A stretched film having a thickness ratio was produced. Next, the stretched film is treated with hot air of 75 ° C for 10 seconds in a tube annealing apparatus, cooled to room temperature, folded and wound up. Was.

The stability during stretching was good, there was no vertical movement of the stretching point, no jump of the stretching tube, and no uneven stretching state such as necking was observed. Obtained The stretched film has the properties shown in Table 1 and is excellent in low-temperature shrinkage, and the heat-sealing temperature and Along with the shrinkage tunnel temperature, the force had good packaging machine suitability over a wide temperature range; it was poor in transparency and gloss.

Comparative Example 2

90% by weight of the same linear low-density polystyrene as in Example 1 was used on the surface layer with the same provylene / ethylene random copolymer pedestal as in Example 1. The composition containing 10% by weight of syndiotactic polypropylene was used as an intermediate layer, and stretched at a thickness ratio shown in Table 1 in the same manner as in Example 1. A film was made. This stretched film has a haze of 2.4%, a gloss of 135% and an area shrinkage of 49%, and has good suitability for packaging machines. Was. Next, the stretched film was repelled by a twin-screw extruder.

30 parts by weight of this pellet, 90 parts by weight of the above-described straight-shaped low-density polystyrene and 10 parts by weight of syndiotactic polypropylene In the same manner as in Example 1, Table 1 shows the composition obtained by mixing the above components as an intermediate layer, and the above-mentioned propylene. .Ethylene random copolymer as a surface layer. A stretched film having the thickness ratio shown was obtained. Next, the stretched finolem was treated with 75 pieces of hot air for 10 seconds in a tube ring apparatus, cooled to room temperature, folded, and wound up. The stability during stretching was good, there was no vertical movement of the stretching point or swing of the stretching tube, and no uneven stretching state such as necking was observed. The obtained stretched film has the properties as shown in Table 1 and thus has excellent low-temperature shrinkability and heat seal even in packaging evaluation using a Piro-one packaging machine. Both the temperature and the shrink tunnel temperature showed good suitability for packaging machinery over a wide temperature range, but were poor in transparency and gloss.

Comparative Example 3

The same provylene-ethylene random copolymer as in Example 1 was used as a surface layer, and the same straight-shaped low-density polystyrene as in Example 11 was used at 40% by weight. A composition obtained by mixing 60% by weight of syndiotactic polypropylene was designated as Intermediate S, and a stretched film having a thickness ratio shown in Table 1 was obtained in the same manner as in Example 1. The room was made. This The stretched film has a haze of 2.3 mm, gross; 133%, an area shrinkage of 35%, inferior low-temperature shrinkage, and shrinkage tunnel temperature. It was of a narrow range. Next, the stretched film was repelled by a twin-screw extruder.

30 parts of this re-vett, 40 parts by weight of the same straight-shaped low-density polystyrene, and syndiotactic polypropylene 60 parts by weight of the composition was used as an intermediate layer, and the above-mentioned propylene / ethylene / random copolymer was used as a surface layer. A stretched film having the thickness ratio shown in 1 was obtained. Next, the stretched film was treated in a tube annealing apparatus with 75 pieces of hot air for 10 seconds, cooled to room temperature, folded and wound up.o

The stability during stretching was good, there was no vertical movement of the stretching point or swing of the stretching tube, and no uneven stretching state such as necking was observed. The obtained stretched film had the properties shown in Table 1, and was excellent in transparency and luster, but inferior in low-temperature shrinkage. However, even in the packaging evaluation using a Pillow packaging machine, the shrink tunnel temperature range for obtaining a good finish was narrow.

Comparative Example 4

The same propylene / diethylene random copolymer as in Example 1 was used as the surface layer, and the same linear low-density polyethylene as in Example 1 was used at 70% by weight. A composition obtained by mixing 30% by weight of syntactic polypropylene is used as an intermediate layer, and a stretched film having a thickness ratio shown in Table 1 is produced in the same manner as in Example 1. Lum got. This stretched frame has a haze of 2.6%, a gross of 133%, and an area shrinkage of 45%. At low temperatures, film whitening or arcade (holes in the frame) was observed, and the shrink tunnel temperature range was narrow. Next, the stretched film was repelled by a twin-screw extruder.

30 parts by weight of this revelet, 70 parts by weight of the above-mentioned linear low-density polystyrene, and 30 parts by weight of syndiotactic polypropylene Composition with mixed parts The propylene / ethylene random copolymer described above was used as the surface layer with the product as the intermediate layer, and the thickness of the surface layer was 0.8 m each in the same manner as in Example 1. A stretched film was obtained. Next, the stretched film was treated with 75 pieces of hot air for 10 seconds in a tube annealing apparatus, cooled to room temperature, folded, and wound up.

The stability during stretching was good, there was no vertical movement of the stretching point and no swing of the stretching tube, and no uneven stretching state such as necking was observed. The obtained stretched film had the properties as shown in Table 1, but had excellent transparency and luster, and had low-temperature shrinkage. According to the packaging evaluation using a pillow wrapping machine, the shrinking tunnel temperature was relatively low and the film was whitened or broken (a hole in the film). The shrink tunnel temperature range for good finish was gouged.

Comparative Example 5

As shown in Table 1, a density of 0.890 g Z cm 3, as shown in Table 1, was obtained by using the same propylene (ethylene) random copolymer as in Example 1 on the surface layer. 70% by weight of straight-shaped low-density polyethylene having MI of 0.8 g and 10 minutes by weight of 30%, and 30% by weight of syndiotactic poliprolene. % Blended composition)! Then, a stretched film having a thickness ratio shown in Table 1 was produced in the same manner as in Example 1. This stretched film has a haze of 2.6% gloss; 133% and an area shrinkage of 53%. There was a trouble that the lumps meandered. Next, this stretched film was turned into a pellet with a twin-screw extruder.

30 parts by weight of this revelet, 70 parts by weight of the above-mentioned straight-shaped low-density polystyrene, and 30 parts by weight of syndiotactic polypropylene The composition obtained by mixing the above components was used as an intermediate layer, and the above-mentioned propylene / ethylene random copolymer was used as a surface layer. A stretched film having a thickness ratio was obtained. Next, the stretched film is subjected to 75 by a tube annealing apparatus. After being treated with the hot air of C for 10 seconds, it was cooled to room temperature, folded and wound up. Good stability during stretching, no vertical movement of stretching point or swing of stretching tube Example 1 Example 2 Example 13 Example 4 Comparative example 1 Comparative example 2 Comparative example 13 Comparative example 4 Comparative example 5 Raw material table ifi layer F nf ren · Chief 'of ren · Chief' レン 'ren · Chief' at "vy-if '' pi-bilene · ιchi 'Πbilene · Ιchifu' ot * len · ιchi Prescription renranta A Ren Lanta 'm Ren La' / Ta 'M Leng · 7' Ten Lent L 'k' Len L 'Even

Copolymers Copolymers Copolymers Tertiary Copolymers Copolymers Copolymers Copolymers Copolymer Copolymer Middle A: LLDPE-1 A: LLDPE-1 A: LLDPE- 1 A: LLDPE-2 A: LLDPE-1 A: LLDPE-1 A: LLDPE-1 A: LLDPE-1 A: LLDPE-3 B: S-PP B: S-PP B: S-PP B: S- PP B: PE B: S-PP B: S-PP B: S-PP B: S-PP

C: Collected items C: Collected items C: Collected items C: Collected items C: Collected items C: Collected items Collected items

(Deployment platform (Blending (K blending (Blending (Blending platform (Blending platform (K platform (Deployment signage ratio) Weight ratio) Weight ratio) Weight ratio) Weight ratio) Weight ratio) Weight ratio) Weight ratio) Weight ratio) Weight ratio)

A / BA / B / CA / B / CA / B / CA / BA / B / CA / B / CA / B / CA / B / C = 80/20 = 80/20/30 = 50/50/30 = 70/30/40 = 80/20 = 90/10/30 = 40/60/30 = 70/30/30 = 70/30/30 Thickness Total 15 15 15 15 15 15 15 15 15 μ.m Valley 2 Valley Z Each 2 Each 2 Each 2 Each 2 0.8 Each 1 Haze (X) 2.4 2.8 2.5 2.5 4.9 4.2 1.4 2.7 3.8 Gloss (X) 135 132 134 135 105 115 134 132 117 Area shrinkage X 51 47 41 42 42 49 32 44 53 Suitability for packaging machine O 〇〇〇〇 Om Δ Δ Intermediate layer A: LLDPE-1 (density: 0.916 g / cm ^2. I 1.2 g / 10 min), LLDPE-2 (density: 0.925 g / cm ^2. Ml: 1.6 g / 10 min),

LLDPE-3 (density: 0.900 g / cm ² .MI 0.8 g / 10 min)

B: S-PP (; ン; 'i Tactic 7''/7' nf len)> PE (F'0 ren 'if renrantam co-body)

In addition, non-uniform stretching such as necking was not observed. The obtained stretched film has the properties as shown in Table 1 and has low temperature shrinkage, poor force, transparency and gloss, and In the evaluation of the packaging by the packaging machine, a problem occurred that the finolem meandered. Industrial applicability

As described above, in the polyolefin-based heat shrinkable film of the present invention, the surface layer is made of a crystalline polypropylene resin, and the intermediate layer is made of a linear resin. It is a mixture of low-density polyethylene resin and a specific syndiotactic polypropylene, which is transparent even if the recovered product is mixed in the middle layer. It is suitable as a heat-shrinkable packaging material without a decrease in heat resistance and excellent in low-temperature shrinkage and packaging machine suitability.

Claims

The scope of the claims

1.25. Density in C is 0.91 to 0.93 g / cm ³ , melt indexing power; 0.2 to 3. O gz '10 minutes of ethylene and α — Straight-line low-density polystyrene consisting of olefin (ォ) 80 to 50 parts by weight and syndiotactic polypropylene (Β) An ethylene-based resin composition consisting essentially of 20 to 50 parts by weight is used as the intermediate layer, and the surface layer is made of a crystalline polypropylene resin, and the thickness of the intermediate layer is reduced. A polyolefin-based heat-shrinkable laminated film that is 30% or more of the whole, the thickness of the surface layer is 1m or more, and stretched 2.0 times or more in each of length and width.

. 2 Thin-di O data Cu Chi click Po Li profile ^{1 5} C of pin les down (B) - sheet was measured by NMR down di O data Cu Chi click pen data Tsu de fraction 0. 2. The olefin-based heat-shrinkable laminated film according to claim 1, which is 7 or more.